What I'm thinking is that the state's attorney would reinstate the limited use immunity offer, Casey would tell, then Leonard would reinstate the bond and she would be released. Then she will be rearrested for lying to police about where Caylee's remains are and/or charged with murder or any of the lesser charges they could probably still levy against her.
She might get a day or a few days of freedom while LE searches in the area she gives them, but she definitely would be going back to the pokey. Her bond will be revoked again, and either the new bond will be totally out of reach, even for Leonard, or there will be no bond at all if she's charged with murder.
It is a no-win for Casey -- not worth giving up info that would further incriminate her in order to go home for a day or two before being charged with murder. She'll never agree to Leonard's terms.